In the field of oil refining, the catalysts have preferably a more or less high converting activity which, after periods of use, tends to decrease while the coking activity continually increases.
These catalysts may be classified in two groups, respectively concerning the fields of catalytic cracking and hydrotreatment, respectively.
For characterizing cracking catalysts, it is known to use the so-called M.A.T. test (Micro Activity test) described in standard ASTM D 39-07. This method is time-consuming since it requires, in order to obtain a balance, an intermediate simulated distillation over a chromatography column and an ex-situ analysis of the residual coke over a carbon analyzer, making it difficulty reproducible.
The tests for characterizing hydrotreatment catalysts are conducted under high pressure in the presence of hydrogen, followed by elementary analysis. Such tests are very costly and usually last about fifteen days, as a whole.
From the information obtained by these costly and time-consuming tests, the catalyst activity may be identified as a more or less converting activity and correspondingly a more or less coking activity.
The prior art is particularly illustrated by U.S. Pat. No. 4,568,426, EP No. 0 026 012 and U.S. Pat. No. 4,099,923.
U.S. Pat. No. 4,568,426 discloses a sophisticated apparatus adapted to reproduce with accuracy and simplicity the measurement of Conradson carbon (CCR) obtained by heating the sample in inert atmosphere, purging the gaseous products in an inert atmosphere and weighing the residue.
EP No. 0,026,012 discloses a method for determining the API density of an oil by vaporization of volatile and pyrolyzable compounds and by measurement of the hydrocarbon amount within a temperature range of for example 350.degree.-750.degree. C., in proportion to the total vaporized amount.
Finally, U.S. Pat. No. 4,099,923 discloses a unit for catalyst preselection in the presence of hydrocarbons alone or in the presence of ammonia or air or of both gases. An aliquot part of the reaction gas is separated from solids and liquids and transferred to a gas chromatograph where it is analyzed.